In the case of a currently marketed container constituted of a polyethylene single layer, a polyethylene terephthalate single layer or the like and having itself no light-shielding performance imparted, a light-shielding performance is imparted to a shrink film or another bag to prevent deterioration of contents due to ultraviolet-ray.
When alternate members such as a shrink film, another bag and the like are used, however, the cost increases, thus, there is a need for a light-shielding container having itself a light-shielding performance imparted.
There are documents disclosing light-shielding containers endowed with a light-shielding performance, as technical documents applied prior to the present invention (see, e.g., patent document 1 (JP-A No. 5-139434), patent document 2 (JP-A No. 7-40954) and patent document 3 (JP-A No. 2003-341748)).
In the above-described patent document 1, a polyethylene material constituting a container is blended with a white pigment or an ultraviolet absorber. By this, a container can be provided which prevents oxidative deterioration of a liquid fuel and in which the amount of a liquid fuel in the container can be easily confirmed.
In the above-described patent document 2, a light-shielding container is constituted of two layers: a layer (a) composed of a thermoplastic resin (A) and a layer (b) composed of a thermoplastic resin composition (B) containing an ultraviolet absorber, the layer (b) acting as an intermediate layer. By this, a light-shielding container can be obtained which has excellent transparency and mechanical strength, successfully blocks ultraviolet ray having a longer wavelength than 290 to 320 nm, and in which the ultraviolet absorber does not migrate into contents, thereby causing little mold pollution with the ultraviolet absorber.
In the above-described patent document 3, it is possible to provide a container having an inner layer composed of a thermoplastic resin containing a pigment having a light-shielding property and an outer layer composed of a thermoplastic resin containing a pigment having hue different from that in the inner layer, wherein a sufficient light-shielding property and any coloration of the exterior surface of the container are satisfied simultaneously by regulating the materials of the pigment having a light-shielding property and of the thermoplastic resin.